This version of the Audio Karma Econowave uses an Eminence Delta 12 LFA woofer with the recommended Selenium compression driver and a Dayton waveguide. It's 4 cu ft enclosure is optimal for this woofer, and with 95dB sensitivity it is easily driven to room filling levels by that 3 watt Bottlehead 2A3 SET amp pictured beside it.
This rear view shows the rear firing tweeter, an Eminence ASD-1001 compression driver and a Dayton 7" waveguide crossed at 2.7Khz, the 4" X 1.5"long port, and the speaker terminals. I found the rear firing tweeter didn't add much if anything to the sound, and I later removed it.
The Zaph Audio Budget Aluminum MTM.